Attached are some pics of my #3 plug. I pulled some more and they all look the same. They have abt 20K miles on them. One side looks almost white, the other looks like something is building up on it. Would detonation only effect one side of the plug, or it from fuel additives, or ????

 

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That's OK from what I can see (pics are for the old guys are hard to focus on).

20K?.
That's probably about 2x as long as I'd ever run a plug. As they degenerate the center electrode loses it it's edges, and raises the min firing voltage. For a soccer mom driving no biggie but for a good engine, I like to treat them well.

The other plugs look to have alot of ash on them. Usually an indicator of oil being present in the combustion chamber. When you start running plugs with that much ash on them, they can generate hot spots in the chamber, and lead to preignition, which is a huge no-no, and Knock Sensor is deaf to most preignition events. Again, a good reason to change plugs more often.

Indexing plugs often gets them to look more like each other. Sometimes the center elelctrode masks part of the porclean so it looks to be burning in a 1/2, and 1/2 fashion.

IMO, FWIW, YMMV....

 

It does look like you're burning some oil. From the high ash build-up I'm guessing you're running some conventional oil and not synthetic? It's just a guess but am I right?
I'm with Grumpy. I replace my plugs at least twice a year on anything that I own... except the new cars. They seem to be good for about 60k miles.

 

Yeah, thats oil.

3 out of 4 look like that on the Saturn when I yank them out :-)

Even swap them from bad hole to worse hole just to get some extra life. I even scrub them off and use a plug clenaer on them till I see pitting and rounding of the edges. Yet I dont care it gets 30 mpg and is a POS :-)

But I second the semi frequent plug changes also. Specially depending on how close to the edge u like to push it and they are cheap insurance at $10-12 a set.

later
Jeremy

 

Yep oil, I've noticed that when you get oil on just one side of the plug it's usually from leaky valve guides. Your getting the oil spray from one direction that causes the build up on just one side of the plug as oposed to an even coating like my plugs get from blow by. Do you get smoke at startup? You might try a set of valve guide seals.

 

Thx for the replies!

Good to hear it's just oil build-up. I have recently been leaning out my highway fuel mode and thought I may have went too far.

The eng has 20K miles since the rebuild and those are the original plugs. Eng still runs good, but it's definately time to replace them.

I've only had Valvoline 10-30 in it except for break-in when I used Valvoline 30wt.

When I set the compression ring end-gaps, I leaned toward the big side, more-so for the top ring since the pistons are hypers. This lead to more blow-by than I wanted. Oil dipstick used to come up during WOT, but doesn't do that anymore. Guess the rings finally seated a little better.

I noticed that I'm still getting some oil into the plenum from the breather hose. I saw it accumalating in front of the throttle blades when I was installing a cold air induction set-up last week. I'm assuming that's where the plug ashing problem is coming from. Eng doesn't smoke at all that I can tell. I recently built/installed a catch can for the breather hose. Hopefully that will help some.

 

Might consider installing a good oil vapor/ air seperator. Oil in the combustion chamber, doesn't do the engine any good. All a good one takes is a pint can, 2-3/8" hose fittings, and some stainless steel Steel wool. Solder one of the fittings in, mic can, and then one at the top. From the PCV valve go to the mid can fitting, and then from the top to the TB. Depending on where you install it, you can point the original cap downward, making it easier to empty when necessary.

 

Valvoline's oil line-up has more ash than anybody else. Castrol GTX has just a smidge more but the rest of Castrol's line doesn't have much. Suprise suprise

Like Grumpy said, get a catch can, it works.

 

If you think thats bad, you should see what the tops of your intake valves probably look like. I had aftermarket valve covers with very little in the way of baffles and there was so much oil sludge in the intake runners and on the valves that it was rediculous. It practically blocked half the intake port. This was after about 30k.

 

In a properly sealed engine, oil shouldn't be carbonized. What little *normally* gets past the rings, etc, hasn't been a problem, at least for me in the 30+ years, I've run Valvoline.

Some specs are just kind of over the top, IMO, like the Mobil One ad where they talk about it not breaking down at temps of 400+d. If your oil temp has gotten to that sort of temps, there's some serious issues that need to be addressed.

 

Valvoline is FINE. I wasn't implying it was a problem, just stating that out of all of the plugs that I've seen, the ashy oils build up more ash on the plugs than the synthetics and low additive conventional oils. Castrol GTX does the same thing to my plugs after about 15k miles, and that was with a HOT plug. Since going to the normal heat range I was seeing more ashy build up on all of the plugs. It made it hard to read the electrode but it brushes right off. The synthetics are great stuff and now that they are offered in longer change intervals it actually SAVES you money. I'm still running conventional oil but only because I like taking apart my oil filter. On the other cars they're getting synthetic and oil filter changed every 10k miles... tolerances are so good and a warranty helps .

 

Replaced the plugs (AC43ts) and now I have more issues. As soon as I fired it up after the plug change, it started running real rough. Verified firing order (even though I only pulled one wire at a time during plug change). Checked spark from #8 plug wire and it was strong. Pulled cap and rotor, they look fine. Checked for vacuum leaks, couldn't find any. Dribbled water on header tubes.
On #2 and #8 the water takes ~10 secs to evaporate. #4 and #6 boil the water instantly.
On the road it feels like one or more cyls will intermittently try to fire.

BLMs went from 128 at idle to 112. Wb o2 went from 14.4 to 15.25.. IAC counts went from 5 to 55.
(ECM o2 sensor measures drivers side only. Wb 02 reads both banks)
I disconnected the IAC at abt 1000 rpm.
Pulled inj plugs one-at-a-time. No change in rpms when #8 and #2 were pulled. Swapped spark plugs around, no change. Swapped plug wires around, no change.
Swapped fuel inj plugs between 8 and 6, and 2 and 4. No change, #2 and #8 cyls still dead.
Checked compression on #8 and it was good.
Removed plenum and runners. Lifted fuel rail up. Made harness so I could fire multiple injs at the same time. Compared quantity of fuel thru injs between cyls 6 (good cyl) and 8. They were exactly the same.

Any suggestions?? I'm Stumped

 

Cracked porcelain on some plugs prolly from not being quite gentle enough installing them. It could be the porcelain outside the engine or inside the engine.

Just a guess.

 

While doing the plug change, I also painted my homemade Cold Air Induction piping. Starting to wonder if the spray paint may have effected the ECMs 02 sensor. If the 02 sensor is reporting richer than actual, that would lean the mixture (possibly to the point of misfire) and explain the shift in BLMs and WB02 readings.

I'm currently awaiting my new high-flow runner gaskets from Jegs. When they arrive, thinking abt trying to lock ecm in Open Loop and see if eng idles any better.

Anyone know if ingesting paint fumes would "poision" an O2 sensor, making it read high???

 

RednGold86Z>>>>>>>>>>
I would think swapping the plugs around would detect a damaged plug, but I guess anything is possible. I have the old plugs (7 of them at least ) I'll try re-installing them when I get the eng back together.

 

I borrowed another compression tester from a friend and got much better readings. Guess my old compression tester has a leak.
All cyls at 185-195 psi except #4 and #8.

#4 is 107 and #8 was 120.
Squirted oil in cyls and re-tested.
#4 went to 130. #8 went to 200 psi.

Pulled the pass head off. #4 cyl has either a crack or a gouge running lengthwise up and down the cyl wall.

Don't see anything obvious with #8 cyl wall. I'm guessing it has a broken compression ring.
Looks like I'll be replacing the block.

 

Or punching it out 30/40/60 over.